The present disclosure relates generally to fueling power generation systems. In particular, the present disclosure relates to purging fuel circuits of a power generation system.
A power generation system, such as a gas turbine system, may include multiple fuel circuits, some of which may be enabled and/or disabled during operation of the power generation system. When a fuel circuit is disabled, it may be purged (e.g., with an inert gas) to prevent a safety issue. If the fuel circuit contains unburned fuel, which can mix with air in the fuel circuit via backflow and/or diffusion through a fuel nozzle, purging the fuel circuit may prevent a flame/explosion hazard in the fuel circuit given a source of ignition. Additionally, residual fuel stored at high temperatures may form deposits or otherwise clog the fuel circuit. When a disabled fuel circuit is subsequently enabled, fuel may fill the fuel circuit and empty the inert purge gas before the fuel is delivered to a combustion system of the power generation system. This event is called prefill, and occurs in a finite duration of time.
The fuel exiting the fuel circuit during the purge event enters a combustion system of the power generation system. If the purged fuel is not compensated for by reducing a similar amount of fuel to the combustion system, then the power generation system will output undesired increased power due to the purged fuel. While the purge event may be compensated for by reducing fuel flow (e.g., via other fuel circuits) to the combustion system during the purge event, the amount of fuel flow reduction may vary over the life of the power generation system. This may be because components of the power generation system that introduce fuel to the combustion system may degrade or otherwise change from use and time. For example, gas control valve operating characteristics may change, or fuel circuit volumes, fuel nozzles, fuel passage components, and the like, may collect deposits and/or erode, changing characteristics related to fuel passage. Moreover, maintenance, cleaning, and restoration procedures may also change characteristics related to fuel passage.